Relevance to health and the VA mission: Many of our clients at the VA Palo Alto Mental Health Outpatient Services for PTSD are veterans of Iraq, who need help with hyperarousal symptoms. This study will fill in gaps in our knowledge about the physiology of these symptoms and about the efficacy of relaxation therapies. Non-pharmacological treatments like the ones that we propose may relieve patients' hyperarousal to an extent that they are less tempted to turn to alcohol or sedative drugs. Physiological proof of the effectiveness of relaxation procedures in this clinical group would help convince clinicians to apply them and patient consumers to try them.